Post-Hardy, someone once remarked, Dorsetshire peasants acquired the vanity of the artist's model. The same could be said of the inhabitants of Wyoming in the wake of Annie Proulx and other anatomists of the modern American west. Those burger-bar waitresses, the ketchup stains mingling with the carmine of their finger-nails - you can just see them meditating the deft one-liner that will send their slack-jawed male clientele reeling. Those white-haired ranchers staring quizzically out across the landscape - you can just feel them itching to light out into a movie starring Robert Redford. And sure enough, Uncle Bob (along with Jennifer Lopez) will be taking a starring role in An Unfinished Life 's forthcoming translation to celluloid.

In fact, Mark Spragg's second novel begins a couple of states away, down in the Iowa boondocks where the girls work in dry-cleaners and come home to taut, trailer-park unease, while the guys put up roadside guard-rails for the county and wonder if a pizza-cum-video take-out will serve as the garnish to a quiet evening in. Here we find Jean Gilkyson and her sharply observant pre-teen daughter Griff, the latter busily inscribing in her diary THINGS I HATE ABOUT MY MOTHER ("1. I hate that she's pretty. 2. I hate that she thinks she's not pretty..."), the former, having sustained one slap around the head too many from sinister live-in beau Roy, deciding that it's time to leave town for the only refuge she knows.

The bolt-hole, several hundred miles distant and reached with the help of a friendly biker, turns out to be deeply insecure: not merely because of its proximity to outraged, lovelorn Roy ("Baby, I love you more'n my own life. If I thought you hated me I don't know what I'd do") but also owing to the deep familial tensions that course through its Spartan interiors. Ranch-owner Einar loathes his daughter-in-law for her part in the road accident that claimed the life of his adored only son. Blood, however, turns out to be thicker than water. Charmed (inevitably) by his previously unknown grand-daughter, Einar maintains a state of armed truce with her mom. Jean, meanwhile, seeks solace in the arms of the local sheriff, while both newcomers are joyously welcomed by the ranch's other occupant, a philosophic black cowboy named Mitch Bradley, who once served with Einar in Korea and now lies in a morphine-haze in the bunkhouse, having been badly chewed up by a vagrant grizzly.

If all this sounds faintly predictable, the fault lies not so much in the phantom screenplay that lurks at the margin of every page, or in the somewhat arch lines of dialogue, but in the elemental nature of the human geometry that runs alongside. In the hands of an Annie Proulx this kind of bleak backwater realism, in which Mom will infallibly pick the wrong boyfriend and the gas-station always fails, is given zest by a rococo oddity of weird names and glamorously deviant behaviour. Despite promising nods in this direction, notably the pistol-packing sheriff's assistant Starla ("Wyoming's the best state there is to shoot a man," she explains to Jean), Spragg tends to play safe with his characters who, unlike most of the local livestock, are rarely given enough space in which to roam.

Something of this reined-in quality can be detected in the novel's finale, in which two entirely foreseeable revenants (Roy and the bear) turn up in town. The best parts of An Unfinished Life, oddly enough, are its ancillary details - Einar's routine around the ranch, the desultory clutter of the sheriff's office - and the glimpses of the communal world that exists beyond its immediate focus, full of ground-down lives and soured destinies. Here, in half-a-dozen crisp little vignettes of small-town life (Einar being harassed by a couple of juiced-up teenagers in a street café, Jean and her friend Nina alcoholically raising the demons of their past), the novel loses its faintly generic quality and starts to work on its own terms.

A minor point, perhaps, but the accompanying puff from Kent Haruf ("one of the truest and most original new voices in American letters") would carry slightly more weight if its author were not the book's dedicatee.